1. Field of the Invention
The present invention relates to a magneto-generator for generating electric energy under the action of electromagnetic induction taking place between magnets mounted on a flywheel and an armature winding through rotation of the flywheel.
2. Description of Related Art
For having better understanding of the concept underlying the present invention, description will first be made of a conventional flywheel type magneto-generator by reference to FIGS. 6 and 7 of the accompanying drawings, in which FIG. 6 is a top plan view showing partially in section a rotor of a conventional flywheel type magneto-generator which is disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 121380/1992, and FIG. 7 is a vertical sectional view of the same taken along a line VII—VII shown in FIG. 6 as viewed in the direction indicated by arrows.
Referring to the figures, a rotor of the magneto-generator includes a flywheel 1 implemented in a substantially bowl-like shape (hereinafter also referred to as the bowl-shaped flywheel only for the convenience of description), four magnets 2 mounted on the inner peripheral surface of the flywheel 1 with equidistance therebetween in the circumferential direction, a guard ring 3 of a substantially cylindrical shape which is formed by drawing a sheet metal and closely or tightly fit onto the inner surfaces of the magnets 2 which are disposed substantially in an annular array, a magnet securing resin 4 filled in the space defined between the flywheel 1 and the guard ring 3 at both sides and between the adjacent end portions of the individual magnets 2 for fixedly securing the magnets 2 and the guard ring 3 to the flywheel 1 in a so-called integrated structure, a hub or boss 5 formed in the flywheel 1 at a center portion of a bottom wall 1a for coupling the flywheel to a rotatable shaft (not shown), and a plurality of fins 4a disposed on the bottom wall 1a of the flywheel 1 with equidistance along the inner circumferential surface of the guard ring 3 for the purpose of generating air currents (also referred to as airflow or currents of gas or the like) for cooling a generator coil (not shown) disposed internally of the flywheel 1.
In the magneto-generator of the structure described above, the flywheel 1 is caused to rotate upon rotation of the rotatable shaft (not shown) coupled to the boss 5, whereby electric energy or electricity is generated under the action of electromagnetic induction taking place between the magnets 2 and the generator coil (not shown) disposed internally of the flywheel 1.
In accompanying to the rotation of the flywheel 1, the fins 4a disposed on the bottom wall 1a of the flywheel 1 rotate for thereby agitating a gas (air) existing within the interior space of the flywheel 1, as a result of which the generator coil (not shown) heated, for example, due to a core loss is cooled.
In the conventional magneto-generator of the structure described above, the gas or air existing internally of the flywheel 1 can certainly be agitated. However, no ventilation holes (air holes) are formed in the flywheel 1. Besides, no flow can forcibly be brought about in the gas or air existing externally of the flywheel 1. For these reasons, ventilation internal of the flywheel 1 can not sufficiently be effectuated in the conventional magneto-generator.
On the other hand, the armature winding serving as the generator coil undergoes heating in proportion to the square of the current generated. Thus, when exchange of the heated gas is not adequately effected due to poor ventilation as mentioned above, then the electrical resistance of the winding increases due to temperature rise thereof, which results in lowering of the efficiency of electricity generation, giving rise to a problem.